Oscillators based on crystal resonators have been well known for several decades. Such devices have revolutionized several different technologies such as frequency control devices, thermometers and precision time pieces. However, the performance of all crystal resonators are limited by several different environmental conditions; these conditions include temperature, pressure, acceleration, radiation, time, electromagnetic energy, and humidity. To compensate for effects that these environmental conditions cause in the performance of the crystal resonator, several different variations of crystal resonators have been developed. Examples of these developments include ovenized oscillators, specially cut crystal resonators, various resonator mounting configurations, as well as various electrode configurations.
One well known electrode configuration, which is material to the present invention, is an "electrodeless" configuration wherein the electrodes used to excite the crystal do not physically contact the crystal, that is, there is a gap between the crystal and the electrode. This type of configuration is beneficial because the use of the gap between the electrodes and the crystal reduces the instabilities associated with changes in electrode stresses and at the electrode-quartz interface and therefore, a very high precision and stability can be achieved. This type of electrode configuration is more fully described in U.S. Pat. No. 3,339,091, issued to Hammond et al on Aug. 29, 1964 and U.S. Pat. No. Re. 26,707, issued on Nov. 4, 1967, both of which are incorporated by reference hereto. Other related improvements to this electrode configuration are found in such articles as "A New Piezoelectric Resonator Design," Besson, Proceedings of the 30.sup.th Annual Frequency Control Symposium, pp. 78-83, 1976, which describes an electrodeless "BVA" configuration. One problem with these "electrodeless" configurations, however, is that they still must be mechanically mounted and bonded to a support structure. In so mounting the resonators, the resonators are still subject to stress related instabilities.
The present invention addresses this problem.